1. Field of the Invention
The present invention relates to new and improved phosphorus containing flame retardants.
2. The Prior Art
The technology involved in flame retarding of rigid urethanes has progressed rapidly in the past twenty years. Despite many efforts to find new approaches to flame retard urethanes, however, those approaches requiring phosphorus and halogen compounds remain dominant.
Urethane flame retardants in today's marketplace must be low in cost and have high flame retarding efficiency. Also, they should not have an adverse effect on the urethane components, the resin forming process or the physical properties of the resulting foam.
Some relatively low cost reactive intermediates which can be readily converted to effective flame retardants, but have not received much notice in the past are phosphorus containing aldehydes and ketones. They are particularly effective, reactive intermediates that can be utilized to make flame retardants for polyurethanes.